1. Field of the Invention
The present invention relates to an electronic device using a touch-sensitive screen as an input unit, a digital still camera, and a display control method.
2. Description of the Related Art
With conventional digital still cameras, operations associated with flash setting, zooming photography, and reproduction of images (image-by-image forwarding, enlargement, reduction, etc.) are performed through the use of buttons provided on the back or top of the camera body.
Even if the demands increase for increasing the performance or functions of such digital still cameras and reducing their size, it is very difficult to meet such demands at the same time.
That is, to increase the performance or functions, it is required that more buttons be provided or the operation menu be nested deeply. In addition, to reduce the size, it is required to decrease the number of buttons and nest the operation menu more deeply.
However, increasing the buttons is against downsizing. Nesting the operation menu deeply results in poor operability.
At present, therefore, digital still cameras have been devised which use a touch screen as input means instead of increasing mechanical buttons. As the touch screen, use is commonly made of a pressure sensitive type which has a resistive film as disclosed in, for example, Japanese Unexamined Patent Publication No. 2000-341572.
The touch screen is constructed such that a transparent touch screen is placed on the surface of the liquid crystal display on the back of the digital still camera. By allowing the liquid crystal display unit to display a captured image and an operation menu, a function corresponding to an option touched by the user can be performed.
There will be two main methods for operating the touch screen. One method is to touch a command on the menu displayed on the liquid crystal display unit with a finger or pen, allowing a function corresponding to that command to be carried out.
When the user touches an arrow mark or the like displayed on the liquid crystal display while a still image is being reproduced, a function of forwarding to the next still image or making a return to the previous operation menu can be implemented. This method of operation is referred to as the so-called tapping operation.
The other operation method will be a tracing operation by which a finger or pen placed on the touch screen is moved left, right, up, or down. This operation allows characters to be entered or a display image to be moved at will. This operation method is referred to as the so-called dragging operation.
Thus, the methods for operating the touch screen include the tapping operation and the dragging operation. The touch screens placed on digital still cameras have their operating areas made very small, say, of the order of 1.5 inches.
When the dragging operation area and the tapping operation area are mixed, therefore, a misoperation is liable to occur in that the tapping operating area is touched when the dragging operation is performed.
Specifically, when the tapping operation area is formed in a corner of the display screen and the other area of the display screen is used as the dragging operation area, careless touching of the tapping operation area while the dragging operation is being performed would cause unintended commands to be entered through tapping operations.
For example, suppose that arrow marks for image-by-image forwarding and making a return to the preceding display mode are displayed on the tapping operation area and the dragging operation area is in a mode to reduce or enlarge an image. Then, it might be possible that, while an image is reduced or enlarged, image display is advanced unexpectedly to the next image or a return is made to the preceding display mode.